This application represents the competing renewal of the Boston Obesity/Nutrition Research Center. The Boston Obesity/Nutrition Research Center represents a collaboration of four major institutions representing three major universities in Boston, all located within a 1.5 mile radius of each other. The Boston Obesity Center includes the New England Medical Center, the Beth Israel Deaconess Medical Center, the Harvard School of Public Health, and Boston Medical Center. The institutions represent respectively Tufts University, Harvard University, and Boston University. The Boston Obesity/Nutrition Research Center consists of five Core Laboratories. These includes an Epidemiology Core, directed by Dr. Graham Colditz at the Harvard School of Public Health, a Clinical/Metabolic Core, directed by Dr. George Blackburn at the Beth Israel Deaconess Medical Center, a Body Composition/Energy Expenditure Core, directed b Dr. William Dietz at the New England Medical Center, an Adipocyte Core, initially designed as a Cellular Biochemistry Signal Transduction Core, at Boston Medical Center, now directed by Dr. James Kirkland, and a Transgenic Core at the Beth Israel Deaconess Medical Center directed by Dr. Jeffrey Flier. The Obesity Center offers multiple opportunities for education and training in obesity research to fellows on training grants held by Obesity Center investigators in each of the collaborating universities. The investigators represented in this application hold 65 funded R0-1 grants, approximately 45 which are directed at the study of obesity, energy metabolism or other nutritional disease. In the past four years, Boston Obesity Center investigators have published 135 papers with Center support. Twenty percent of the Obesity Center budget provide support for pilot and feasibility studies. Pilot and feasibility award recipients have published almost 50 papers and received a total of 7 grants from NIH or other funding agencies based on the data obtained from their Center funded investigations.